JP2575616B2 - Thin film magnetic head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film magnetic head in which a plurality of conductor coils are stacked between lower and upper magnetic layers constituting a magnetic circuit.

[Background of the Invention]

In order to increase the recording density per unit area in a magnetic recording / reproducing apparatus such as a magnetic tape recording / reproducing apparatus, it is indispensable to develop a magnetic head in addition to improving the characteristics of a recording medium itself such as a magnetic tape.

As a magnetic head for high-density recording and reproduction, a thin-film magnetic head is known.

FIG. 4 is a sectional view perpendicular to a sliding surface of a magnetic tape for explaining an example of the structure of a conventional thin film magnetic head, wherein 1 is a substrate, 2 is a lower magnetic layer, and 3 is a non-magnetic layer for defining a gap length. Insulating layer, 4 is an upper magnetic layer, 5 ₁ and 5 ₂ are conductor coils, 6
Denotes an insulating layer, 7 denotes a front gap, 8 denotes a back gap, and 9 denotes a magnetic tape sliding surface (hereinafter simply referred to as a tape sliding surface).

In the figure, the thin film magnetic head, the lower magnetic layer 2 due permalloy on a substrate 1 of a non-magnetic is formed, further conductive coil 5 ₁ are insulated from each other by an insulating layer 6 of non-magnetic thereon, 5 ₂ The upper magnetic layer 4 is formed on the insulating layer 6. The lower magnetic layer 2 and the upper magnetic layer 4 form a magnetic circuit. On the tape sliding surface 9 side, the lower magnetic layer 2 and the upper magnetic layer 4 face each other via the extremely thin insulating layer 3 to form a front gap 7. Has formed. The portion of the tape gap 9 of the front gap 7 functions as a head gap, and the thickness of the insulating layer 3 defines the gap length of the head gap. Further, even in the side opposite to the front gap 7 to the conductor coil 5 _1, 5 _2, are connected to each other through the insulating layer of very thin non-magnetic lower magnetic layer 2 and the upper magnetic layer 4, which is the back gap 8
Is formed. (Note that the back gap 8 need not be provided with an insulating layer.

In the thin-film magnetic head having such a structure, deterioration of the magnetic characteristics at the tapered portion of the upper magnetic layer 4 shown in the drawing, reduction of the layer thickness, and magnetic leakage between the upper magnetic layer 4 and the lower magnetic layer 2 are prevented. In the vicinity of the front gap 7 and the back gap 8, the taper angles α and β formed by the upper magnetic layer with respect to the lower magnetic layer 2 are set to 30 ° to 50 °, and the conductor coil 5 is formed on the surface of the insulating layer 6. _1, 5 ₂ so as not to cause the stepped portion by the conductor coil 5 _1, 5 ₂ parts P over tapered surface from the flat surface of the top, has a Q of whether smooth Mera.

Conventionally, when manufacturing such a thin film magnetic head, "IB
M Disk Strage Technology "Feb.1980pp.3-5 (David
A. Thompson and Lubomyr T. RomanKiw “Film Head Devel
opment "or" J. Appl. Phys. 53 [3] March 1982 p
p.2611-2613 (Y.Noro, I.Ohshima, M.Saito, M.Yamada an
d K.Tanaka “Fabrication of a multitrack thin-film
head ") as disclosed, for example, as the insulating layer 6, using an organic material such as photoresist systems organic or polyimide resin, by this organic spin coating, the step due to the conductor coil 5 _1, 5 ₂ The surface is flattened, taper etching is performed to set the taper angles α and β, and the thickness of the insulating layer 3 in the front gap 7 and the thickness of the insulating layer in the back gap 8 are set.

According to the conventional technique, the surface of the insulating layer 6 is sufficiently smooth, but the surface of the photoresist-based organic material is 25%.
Since organic materials generally have a low melting point of 0 ° C. and 350 ° C. for polyimide resins, when such an organic material is used for the insulating layer 6, it is necessary to adhere a protective plate (not shown) to the upper magnetic layer 4. For this bonding, glass bonding, which is a very simple method, is used, but since this method requires an extremely high temperature, it is difficult to use it when an organic material is used for the insulating layer. It is.

On the other hand, the proceedings of the Institute of Telecommunications
-28 as disclosed in (Hiroyuki out seven Uchida "thin film multi narrow track magnetic head"), thin-film magnetic head using an organic material such as SiO ₂ insulating layer 6 has been proposed.

However, in this thin-film magnetic head, an insulating layer of SiO ₂ and a conductor coil are alternately formed on the lower magnetic layer, and when the conductor coils are formed while being insulated from each other, these insulating layers have a thickness of about 0.5 μm. There is a drawback that recording and reproduction efficiency is low because there is only a small size.

That is, as shown in FIG. 5, when the conductor coils are laminated in two layers, a part of the insulating layer 6 is etched to form the front gap 7, and the insulation from the front gap 7 due to the step of the conductor coil is caused. In a region X of the layer 6 up to the tapered portion R, the thickness of the insulating layer 6 is the sum of the thicknesses of the insulating films 6 ₁ , 6 ₂ , and 6 ₃ sequentially formed, and is 1.5 μm.
Since it is very thin, ie, m, the space between the lower magnetic layer 2 and the upper magnetic layer 4 is very small. Therefore, in this region X, the leakage magnetic flux between the lower magnetic layer 2 and the upper magnetic layer 4 increases, and the recording and reproducing efficiency decreases.

In order to eliminate this defect, the front gap 7 may be formed from the tapered portion R of the insulating layer 6 and the region X may be removed. However, for this purpose, it is necessary to perform etching very close to the tapered portion R. is there.

However, the film quality at the tapered portion R of the insulating layer 6 is such that the inclination angle (α in FIG. 4) cannot be set as described above due to the step of the conductor coil at the tapered portion R.
The quality of the film in the flat portion is very poor, and therefore, the etching of the tapered portion R proceeds more rapidly than in the flat portion, and the etching cannot be performed satisfactorily.

On the other hand, Japanese Patent Application Laid-Open No. 55-32203 discloses a thin-film magnetic head using a conductor coil having tapered edges. This thin-film magnetic head has a silicon
An insulating film of O ₂ or the like is formed with a thickness of, for example, 0.1 to 0.5 μm, a first-layer conductor coil is patterned thereon, and both edges are taper-etched, and the same insulating film is further formed thereon. After the formation, the second-layer conductor coil is patterned and both edges are tapered. Hereinafter, similarly, the insulating films and the conductor coils are alternately formed.

By the way, when taper etching is performed on both edges of the second and lower conductor coils, the tapered portion of the insulating film formed so far is also immersed in the conductor etchant. Since the tapered portion of the insulating layer is very thin and has a low density and poor film quality, the conductive etchant penetrates the tapered portion and also etches the lower conductive coil formed so far. become.

As described above, the conventional thin-film magnetic head has problems in manufacturing and structure, has low performance and reliability, and cannot increase the manufacturing yield.

[Object of the invention]

An object of the present invention is to provide a thin-film magnetic head which solves the above-mentioned drawbacks of the prior art, is excellent in performance and reliability, and can increase the production yield.

[Summary of the Invention]

In order to achieve this object, the present invention, between the lower magnetic layer and the upper magnetic layer, alternately laminating a plurality of conductor coils tapered at both edges and a sufficiently thick insulating film, And disposing the conductor coil on a flat portion of the insulating film;
The insulation between the conductor coils, between the conductor coil and the lower and upper magnetic layers is enhanced, and the distance between the lower magnetic layer and the upper magnetic layer is made sufficiently large to reduce the leakage magnetic flux therebetween. During taper etching of both edges of the conductor coil,
It is characterized in that the conductor etchant can be prevented from penetrating the insulating film.

(Example of the invention)

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a thin-film magnetic head according to the present invention. The parts corresponding to those in FIG. 4 are denoted by the same reference numerals, and a plurality of thin-film magnetic heads are formed on a common substrate 1. Shown as a multi-gap thin film magnetic head. In the figure, reference numerals are assigned only to the thin-film magnetic head shown on the right side of the drawing, and the thin-film magnetic head shows a cross section obtained by cutting the right side of the drawing perpendicular to the tape sliding surface.
Hereinafter, one thin-film magnetic head will be described.

In Figure 1, the lower magnetic layer 2 is formed on the substrate 1, the lower magnetic layer two conductor coils 5 ₁ in the form embedded in the insulating layer 6 on the 2, 5 ₂ are laminated. The upper magnetic layer 4 is formed on the insulating layer 6, and the upper magnetic layer 4 and the lower magnetic layer 2 form a magnetic circuit. A thin insulating layer 3 is formed on the tape sliding surface 9 side of the insulating layer 6 so as to obtain a predetermined gap length.
The lower magnetic layer 2 and the upper magnetic layer 4 face each other with the insulating layer 3 interposed therebetween to form a front gap 7. Also, the side of the insulating layer 6 opposite to the tape sliding surface 9 is made thinner (or there is no insulating layer), and the lower magnetic layer 2 and the upper magnetic layer 4 are opposed to each other to form the back gap 8.

The insulating layer 6 is made of a plurality of insulating films (not shown), and these insulating layers are made of, for example, an inorganic substance such as SiO ₂ .
The film thickness is laminated to the conductor coil 5 _1, 5 ₂ and alternating 2μm or more. As described above, since the thick insulating film and the conductor coils 5 ₁ and 5 ₂ are alternately laminated, these conductor coils 5 ₁ and 5 ₂
Mutual, it is increased each insulation between the conductor coil 5 ₁ and the lower between magnetic layer 2 and the conductor coil 5 ₂ and an upper magnetic layer 4, also increases the distance between the lower magnetic layer 2 and the upper magnetic layer 4, front gap 7. Since the taper angles α and β of the insulating layer 6 from the back gap 8 become large, the leakage magnetic field between the lower magnetic layer 2 and the upper magnetic layer 4 in a portion other than the front gap 7 and the back gap 8 is greatly reduced. The recording and reproduction efficiency can be greatly improved.

Both edges of the conductor coils 5 ₁ and 5 ₂ are tapered,
Top (i.e., the upper magnetic layer 4 side) the minimum width of the disposed conductor coil 5 ₂ lower (i.e., the lower magnetic layer 2 side) is set wider than the maximum width of the disposed conductor coil 5 ₁ .

The signal current flows through the conductor coil 5 _1, The bias current flows through the conductor coil 5 _2. This conductor coil 5 ₂
Are common to the thin film magnetic heads formed on the substrate 1. The conductor coils 5 ₁ , 5
An insulating layer is required to insulate between the _two , but for simplicity of the drawing, this insulating layer is not shown.

Next, referring to FIG. 2 showing the manufacturing process of this embodiment,
The configuration and effect of the present invention will be described in more detail. Note that in FIG. 2, 6 _1, 6 _2, 6 ₃ insulating film, 10 an adhesive layer,
Reference numeral 11 denotes a protection plate, and portions corresponding to the portions shown in FIG.

In FIG. 2, a lower magnetic layer 2 having a thickness of about 10 μm is formed by sputtering permalloy on a non-magnetic substrate 1 and then an insulating film 6 having a thickness of 2 μm or more is formed by sputtering SiO ₂ as an interlayer insulating material. ₁ is formed, further thereon,
Al (aluminum is deposited to form an Al layer serving as the conductor coil 5 ₁ of about 3μm thick (FIG. 2 (A)).

Next, by etching the long desired pattern the Al layer in the direction perpendicular to the sheet to form a conductor coil 5 _1. In this case, as both edges along the longitudinal direction of the conductor coil 5 ₁ is tapered with a respective taper angle alpha ', beta', taper etching is performed. After forming the conductor coil 5 _1, the conductor coil 5 ₁ to the entire surface of the insulating film ₆₁ including the SiO ₂ to form a thickness of 2μm or more insulating films 6 ₂ sputtering as an interlayer insulating machine, on which the deposited Al, an Al layer is formed to be the conductor coil 5 ₂ of about 3μm thick (FIG. 2 (B)).

Here, to prevent the deterioration of film quality due to a decrease in the insulating film 6 _{and second} film density at the tapered portion of the edges of the conductor coil 5 _1, and, in order to sufficiently increase the film thickness, both edges of the conductive coil 5 ₁ The taper angles α ′ and β ′ of the portion are set to 45 ° or less.

Next, by etching the long desired pattern in a direction perpendicular an Al layer formed on the insulating film 6 ₂ to the sheet, the conductor coil 5 ₂
To form In this case, as with conductor coil 5 _1, by taper etching, both edges along the longitudinal direction of the conductor coil 5 ₂ is formed in a tapered shape. In this case, the conductor coil 5 ₂ of minimum width (i.e., the width of the surface of the upper magnetic layer 4 side) is wider than the conductor coil 5 ₁ of the maximum width (i.e., the width of the lower magnetic layer 2 side), the insulating film 6 the _second inclined portion conductive coil 5 ₂ is formed so as to completely cover. This is because, as described above, the taper angle of the edges of the conductor coil 5 ₁ α ', β' (FIG. 2 (B))
As 45 ° or less to enhance the film quality of the inclined portion of the insulating film 6 _2,
Although the film thickness is large, the insulating film at this slope is still
6 ₂ of film quality and film thickness has inferior compared to its flat portion, by dipping the inclined portion to the etchant for the conductive coil, is due to the probability of damage of the conductor coil 5 ₁ is higher .

When the conductor coil 5 ₂ is formed, the conductor coil 5 ₂ included in the entire surface of the insulating film 6 _2, an insulating film 6 ₃ or more thickness 2μm of sputtered SiO _2. As described above,
Conductive coil 5 _1, 5 ₂ and the insulating film 6 _and 62, 6 ₃ by the insulating film 6 is formed. Next, taper etching is performed on flat portions B and B 'of the insulating layer 6 on which the insulating films 6 ₁ , 6 ₂ and 6 ₃ are directly laminated,
The thickness of the insulating layer 6 for the front gap 7 and the back gap 8 (FIG. 1) is set (FIG. 2 (C)). Note that the insulating layer 3 in the front gap 7 portion
Is set to about 0.5 μm.

Next, as shown in FIG. 2D, permalloy is sputtered on the insulating layer 6 to form the upper magnetic layer 4 having a thickness of about 10 μm.

Here, the surface of the magnetic layer 6, the inclined portion CC by the conductor coil 5 _1, 5 ₂ '(FIG. 2 (C)) is generated. When the upper magnetic layer 4 is formed in the inclined portions C and C ', the film quality is generally not good. However, the conductor coil 5 _1, the taper angle of the edges of the 5 ₂ alpha ', beta' by setting below 45 ° as before, tilting station C, a tilt angle of the insulating layer 6 in C 'is so It is not large, and the film quality of the upper magnetic layer 4 does not deteriorate. If these taper angles α ′ and β ′ are too small,
Since the conductor coil 5 _1, 5 ₂ of the width relationship is to set as described above, even when set to the minimum required cross-sectional area of the conductor coil 5 ₁ arranged in a lower portion, a conductor disposed above the width of the coil 5 ₂ becomes very large, since this, together with the degree of integration of the head is lowered magnetic circuit by the lower magnetic layer 2 and the upper magnetic layer 4 becomes very long, recording, reproducing efficiency decreases. Therefore, the conductor coil 5 _1, 5 taper angle of the edges of the ₂ alpha ', beta' is set below 45 ° or more 25 °.

On the other hand, the taper angles α and β of the insulating layer 6 from the front gap 7 and the back gap 8 shown in FIG. 2 (D) are from the top to prevent the deterioration of the film quality of the insulating layer 6 formed in the inclined portion. The angle is set to 25 ° or more in order to reduce the leakage magnetic flux between the upper magnetic layer 4 and the lower magnetic layer 2 at this inclined portion.

Further, as shown in FIG. 2 (D), in order to set the thickness of the insulating layer in the front gap 7 and the back gap 8, the insulating layer 6 is formed by flat portions B and B 'shown in FIG. 2 (C).
The taper etching is performed to obtain a desired etching accuracy. Of course, it is conceivable to taper-etch the insulating layer 6 at the inclined portions C and C 'shown in FIG. 2 (C). However, the etching rate at the inclined portions C and C 'is extremely high, and when the thickness of the insulating layer 6 at the front gap 7 and the back gap 8 is set to a specified thickness, these inclined portions C and C' ′, Over-etching or the like occurs. Further, even if the insulating layer 6 is taper-etched at the flat portions B and B ', these flat portions B and B'
In this case, the thickness of the insulating layer 6 is as thick as 6 μm (2 μm × 3) or more, and the leakage magnetic flux between the lower magnetic layer 2 and the upper magnetic layer 4 in these portions can be sufficiently controlled.

After the upper magnetic layer 4 is formed as described above and the head wafer is completed, a low-melting glass layer 10 is formed on the upper magnetic layer 4 and the protective plate is bonded to the low-melting glass layer 10 by heat bonding. 11 is bonded (FIG. 2 (E)). Many low-melting glass materials having a working temperature of about 400 ° C. are commercially available and are not particularly limited. Then, the tape sliding surface is processed into a desired head shape, and a thin-film magnetic head is completed.

In this way, by alternately laminating a thick SiO ₂ insulating film with the conductor coil to form the insulating layer, the leakage magnetic flux between the lower magnetic layer and the upper magnetic layer can be significantly reduced, and the conductor coil and the conductor coil can be separated. The insulation between the coil and the upper and lower magnetic layers is extremely good, and the flat portion of the insulating layer can be tapered, so that the front gap portion and the back gap portion can be formed accurately and easily. be able to.

Assuming that the magnetic flux loss between the lower magnetic layer 2 and the upper magnetic layer 4 is φ _R and the effective magnetic flux is φ, the magnetic flux efficiency η is expressed as φ / φ _{R. As} shown in FIG. For the dimensions of each part of the magnetic layer 2 and the upper magnetic layer 4, the lower magnetic layer 2
Based on the estimation of the magnetic resistance between the magnetic layer and the upper magnetic layer 4, the above-mentioned magnetic flux efficiency η is expressed by the following equation.

As an example of the thin film magnetic head according to the present invention, b = 6
μm, μ = 1000, T = 10 μm, t = 10 μm, W = 50 μm, and η
Assuming that 0.9, the length a of the tapered etched flat portion of the insulating layer is 10 μm. On the other hand, in the conventional thin-film magnetic head, b = 1 μm, μ = 1000, T = 5 μm,
When t = 10 μm, W = about 50 μm, and when η = 0.9, a = 1 μm or less, and it becomes very difficult to perform taper etching of the insulating layer. Also, as is clear from the above equation,
Since the magnetic flux efficiency η decreases as the length a of the flat portion increases,
In the case of the above-mentioned conventional thin-film magnetic head, when taper etching is performed on a flat portion of the insulating layer to form a front gap or a back gap, the magnetic flux efficiency η is greatly reduced. Taper etching can be performed with a margin in this flat portion.

Although the above-described embodiment is a case where the conductor coils are laminated in two layers, the same applies to a case where three or more layers are formed. That is, the plurality of conductor coils are sequentially laminated with a sufficiently thick flat insulating film of 2 μm or more interposed between the lower magnetic layer and the upper magnetic layer, and both edges thereof are 25 ° to 25 °.
Formed in a taper shape with a taper angle of 45 °, when looking at any two vertically adjacent conductor layers, the minimum width of the conductor coil located on the upper side is the maximum width of the conductor coil arranged on the lower side By making it larger, the conductor coil arranged on the upper side also covers the slope of the insulating film on the conductor coil located on the lower side, and etching for conductors on the slope with poor film quality compared to the flat part The effect of preventing intrusion of liquid can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the insulation between the conductor coils and the magnetic layers constituting the magnetic circuit, the insulation between the conductor coils can be sufficiently ensured, and the gap between the lower magnetic layer and the upper magnetic layer can be secured. The gap can be increased, the leakage magnetic flux between them can be sufficiently reduced, the performance and reliability are improved, the manufacturing yield is increased, and the thin-film magnetic head has excellent functions except for the above-mentioned disadvantages of the prior art. Can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a thin film magnetic head according to the present invention, FIG. 2 is a process chart showing a specific example of a manufacturing method of the embodiment shown in FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing an example of a conventional thin-film magnetic head, and FIG. 5 is a fourth view for explaining problems of the conventional thin-film magnetic head. It is principal part sectional drawing of a figure. 1 ... substrate, 2 ... lower magnetic layer, 3,6 ... insulating layer, 4 ... upper magnetic layer, 5 ₁ , 5 ₂ ... conductor coil, 6 ₁ , 6 ₂ , 6 ₃ ... insulating film, 7: Front gap, 8: Back gap, 9: Tape sliding surface, 10: Low melting glass layer, 11: Protective plate.

Claims (1)

(57) [Claims] A plurality of conductive coils are laminated between a lower magnetic layer formed on a substrate and an upper magnetic layer forming a magnetic circuit together with the lower magnetic layer, and a plurality of conductive coils are stacked between the conductive coils and at an uppermost position. In a thin-film magnetic head in which an insulating film is provided between a conductor coil and the upper magnetic layer and between a lowermost conductor coil and the lower magnetic layer, the thickness of the insulating film is made sufficiently thick; Both edges of the conductor coil are taper-etched, and the minimum width of the conductor coil on the upper magnetic layer side is set to be smaller than the maximum width of the conductor coil on the lower magnetic layer side between the conductor coils stacked vertically adjacently. A thin-film magnetic head, wherein the inclined portion of the insulating layer on the conductor coil on the lower magnetic layer side is formed so as to be completely covered by the conductor coil on the upper magnetic layer side.